86 Eminent Physicists

## Kirstine Meyer awarded the Gold Medal of the The Royal Danish Academy of Sciences and Letters in 1899.

From Pia Grüner, MA, Chief of the Secretariat of The Royal Danish Academy of Sciences and Letters, August 2000:

Kirstine Meyer (b. Bjerrum) was awarded the Gold Medal of the The Royal Danish Academy of Sciences and Letters in 1899. Her contribution was published in our series: SN 6.IX.3.(p.155-225). 1899. It was decided to give her the Gold Medal at a meeting on 24 February 1899.

There is an evaluation of the paper in the Academy yearbook of 1899 by Professors Christian Christiansen (1875-1917) and Peter Kristian Prytz (1891-1929). It is in Danish. [The English translation is by Pia Grüner.]

The prize subject was "to examine whether there exists a general equation of state for all fluid bodies." The evaluation then goes on: "This seems to have proved probable by the examinations by v.d. Waals and others. That they all seem more or less concordant has long been well known, but recent examinations have also indicated that a cohesion as simple as the one mentioned by v.d. Waals is hardly to be found.

"The author of the present paper has made this question a subject of thourough discussion. At first he tests if the law in its original form i correct. Due to this the equation of state must assume the same form in all matter, if you use the critical values as unit for volume, pressure and temperature. If you are now aware of these "critical" quantities it is very simple to test the validity of the law. However it is very complicated to measure critical quantities because different sources of error, which probably have no great importance in other circumstances, for instance a minor addition of a permanent gas, might make a big difference at the critical point. The author has made an effort to be independant by using units, proportional to the critical quantities. This result is reached by presupposing that the temperature by which the specific gravity of a liquid is 100 times bigger than the specific gravity of its saturated steam. According to this method he has compared 20 subject matters. The result i that the deviations between the matters are so big that the law of v.d. Waal in its original form cannot be right. Moreover the author tries whether it is possible to ameliorate the connection by chosing other quantities than the critical data. In an ingenious way, which would be too complicated to explain at this occasion, he succeeds in proving that it is in fact possible to get a result in thi way. It turns out that you may keep the critical pressure as a unit, but must choose units for volume and temperature deviating somewhat from the critical quantities. This very extensive and interesting research now reaches to the determination of the new unities, and after they have been found it is easy to prove the validity of the law. The result of this work is then that there must exist a common equation of state for all fluid bodies that can be given the following form: f(p,v + a, T + ß, a, b, c), = 0, where p,v,T are pressure, volume, temperature, a, ß, a, b, c, constants, adjusting to the nature of the matter. It is obvious that the author holds the scientific insight demanded to go through with this work; he has used the available experimental material in a thorough and profound way, and he has presented a genuine answer to the prize offered at a level that we can only hope that the author intends to publish the results. Therefore we can only recommend the Academy that thi work is rewarded with the Gold Medal of the Academy."

C. Christiansen , K. Prytz

Accordingly it was decided to award the author of this paper the Gold Medal of the Academy. By opening the nametag, it turned out that the author wa Mrs Kirstine Meyer, b. Bjerrum, MS.!